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// Copyright (c) 2010-2021 niXman (github dot nixman at pm dot me). All
// rights reserved.
//
// This file is part of YAS(https://github.com/niXman/yas) project.
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
//
//
// Boost Software License - Version 1.0 - August 17th, 2003
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// DEALINGS IN THE SOFTWARE.

#ifndef __yas__mem_streams_hpp
#define __yas__mem_streams_hpp

#include <yas/detail/config/config.hpp>
#include <yas/detail/tools/cast.hpp>
#include <yas/detail/tools/noncopyable.hpp>
#include <yas/detail/type_traits/type_traits.hpp>
#include <yas/buffers.hpp>

#include <cmath>
#include <cstring>
#include <vector>

namespace yas {

    /***************************************************************************/
    // 基于shared_buffer的内存输出流
    struct mem_ostream
    {
        YAS_NONCOPYABLE(mem_ostream)
        YAS_MOVABLE(mem_ostream)

        mem_ostream(std::size_t reserved = 1024 * 20)
            : buf(reserved)
            , beg(buf.data.get())
            , cur(buf.data.get())
            , end(buf.data.get() + buf.size)
        {}
        mem_ostream(void* ptr, std::size_t size)
            :buf()
            , beg(__YAS_SCAST(char*, ptr))
            , cur(__YAS_SCAST(char*, ptr))
            , end(__YAS_SCAST(char*, ptr) + size)
        {}
        mem_ostream(shared_buffer b)
            :buf(std::move(b))
            , beg(__YAS_SCAST(char*, buf.data.get()))
            , cur(__YAS_SCAST(char*, buf.data.get()))
            , end(__YAS_SCAST(char*, buf.data.get()) + buf.size)
        {}

        template<typename T>
        std::size_t write(const T* ptr, std::size_t size)
        {
            if (__YAS_UNLIKELY(cur + size > end)) {
                realloc(size);
            }

            std::memcpy(cur, ptr, size);
            cur += size;

            return size;
        }

        shared_buffer get_shared_buffer() const { return shared_buffer(buf.data, __YAS_SCAST(std::size_t, cur - beg)); }
        intrusive_buffer get_intrusive_buffer() const { return intrusive_buffer(beg, __YAS_SCAST(std::size_t, cur - beg)); }

    private:
        // buffer扩容
        void realloc(std::size_t size)
        {
            const std::size_t olds = __YAS_SCAST(std::size_t, cur - beg);
            const std::size_t news = __YAS_SCAST(std::size_t,
                size + (olds * __YAS_SCAST(std::size_t, ((1 + std::sqrt(5)) / 1.5)))
            );

            shared_buffer::shared_array_type prev = buf.data;
            buf = shared_buffer(news);
            std::memcpy(buf.data.get(), prev.get(), olds);

            beg = buf.data.get();
            cur = beg + olds;
            end = beg + news;
        }

        // shared_buffer是对std::shared_ptr<char>的封装
        shared_buffer buf;
        char* beg, * cur, * end;
    }; // struct mem_ostream

    /***************************************************************************/
    // 基于内存的输入流
    // 内存的形式可以是指针、intrusive_buffer、shared_buffer、std::vector<char>、
    // std::vector<int8_t>, std::vector<uint8_t>等格式
    struct mem_istream 
    {
        YAS_NONCOPYABLE(mem_istream);
            YAS_MOVABLE(mem_istream);

        mem_istream(const void* ptr, std::size_t size)
            :beg(__YAS_SCAST(const char*, ptr))
            , cur(__YAS_SCAST(const char*, ptr))
            , end(__YAS_SCAST(const char*, ptr) + size)
        {}
        mem_istream(const intrusive_buffer& buf)
            :beg(buf.data)
            , cur(buf.data)
            , end(buf.data + buf.size)
        {}
        mem_istream(const shared_buffer& buf)
            :beg(buf.data.get())
            , cur(buf.data.get())
            , end(buf.data.get() + buf.size)
        {}
        mem_istream(const std::vector<char>& buf)
            :beg(buf.data())
            , cur(buf.data())
            , end(buf.data() + buf.size())
        {}
        mem_istream(const std::vector<int8_t>& buf)
            :beg(__YAS_RCAST(const char*, buf.data()))
            , cur(__YAS_RCAST(const char*, buf.data()))
            , end(__YAS_RCAST(const char*, buf.data()) + buf.size())
        {}
        mem_istream(const std::vector<uint8_t>& buf)
            :beg(__YAS_RCAST(const char*, buf.data()))
            , cur(__YAS_RCAST(const char*, buf.data()))
            , end(__YAS_RCAST(const char*, buf.data()) + buf.size())
        {}

        // 读取size字节的数据，存入ptr指向的内存
        template<typename T>
        std::size_t read(T* ptr, const std::size_t size) {
            const std::size_t avail = __YAS_SCAST(std::size_t, end - cur);
            if (size <= avail) {
                std::memcpy(ptr, cur, size);
                cur += size;

                return size;
            }

            return avail;
        }

        std::size_t available() const { return end - cur; }
        bool empty() const { return cur == end; }
        char peekch() const { return *cur; }
        char getch() { return *cur++; }
        void ungetch(char) { --cur; }

        shared_buffer get_shared_buffer() const { return shared_buffer(cur, __YAS_SCAST(std::size_t, end - cur)); }
        intrusive_buffer get_intrusive_buffer() const { return intrusive_buffer(cur, __YAS_SCAST(std::size_t, end - cur)); }

    private:
        // const: 对数据只有读取权限
        const char* beg, * cur, * end;
    }; // struct mem_istream

    /***************************************************************************/

    // 基于std::vector<ByteType>的输出流
    template<typename ByteType>
    struct vector_ostream
    {
        YAS_NONCOPYABLE(vector_ostream);
        YAS_MOVABLE(vector_ostream);

        vector_ostream()
            :owning_buf()
            , buf(owning_buf)
        {}

        // 由外部的buf作为输出容器
        vector_ostream(std::vector<ByteType>& buf_)
            : buf(buf_)
        {}

        // 写入数据
        template<typename T>
        std::size_t write(const T* ptr, std::size_t size)
        {
            // 转为ByteType类型
            const ByteType* cptr = reinterpret_cast<const ByteType*>(ptr);
            // 插入数据
            buf.insert(buf.end(), cptr, cptr + size);
            return size;
        }

        intrusive_buffer get_intrusive_buffer() const { return intrusive_buffer(buf); }

        // ByteType必须是基本类型并且占1个字节，也就是说ByteType可以是char也可以是unsigned char
        static_assert(std::is_fundamental<ByteType>::value && sizeof(ByteType) == 1, "template parameter should be a byte type");
        
        // 实例化时，不传入buf，才会使用owning_buf
        std::vector<ByteType> owning_buf;
        std::vector<ByteType>& buf;
    };

} // ns yas

#endif // __yas__mem_streams_hpp
